Yodanoe desbruyeresi, Bonifácio & Menot, 2019

Bonifácio, Paulo & Menot, Lénaïck, 2019, New genera and species from the Equatorial Pacific provide phylogenetic insights into deep-sea Polynoidae (Annelida), Zoological Journal of the Linnean Society 185, pp. 555-635 : 619-620

YODANOE DESBRUYERESI SP. NOV.

( FIG. 21A–G; TABLES 1, 2)

Type material: Holotype, MNHN-IA-TYPE 1843 ( IFR448 b), complete, length 3.86 mm, width 0.64 mm, 17 segments (including tentacular segment), Equatorial Eastern Pacific Ocean , Clarion-Clipperton Fracture Zone, Ifremer license area, station 158, collected 15 April 2015, epibenthic sledge supra-net, start 14°3.411′N, 130°7.989′W, end 14°3.813′N, 130°6.481′W, 4946–4978 m depth, 3789 m trawling distance.

Description (based on holotype): Holotype complete, 3.86 mm long and 0.64 mm wide for 17 segments (including tentacular segment), dorsoventrally flattened, tapering posteriorly; live specimen slightly translucent, bluish ( Fig. 21A); ethanol-preserved specimen pale white, prostomium whitish.

Prostomium bilobed, about as wide as long, lobes pronounced, anteriorly tapering to triangular peaks, located close to the notch; frontal filaments absent; median notch between prostomial lobes wide and moderately deep ( Fig. 21B); eyes absent. Median antenna present, lateral antennae absent; ceratophore of median antenna, bulbous, large, short (shorter than anterior margin of prostomial lobes), inserted anteromedially on prostomium, in the notch, style missing. Palps smooth, tapering, long (reaching to segment 5; Fig. 21B). Facial tubercles absent; upper lip with few folds.

Tentacular segment with elongate acicular lobe, inserted laterally and slightly ventral to prostomium; with acicula not penetrating epidermis, without chaetae ( Fig. 21B); tentaculophores distinct, large, dorsal pair slightly longer than ventral one, inserted distally; styles missing. Pharynx not everted. Second segment with elytrophores, subbiramous parapodia, with chaetae and ventral cirri.

Eight pairs of massive, cylindrical, elongate (longest on segments 9 and 11) elytrophores ( Fig. 21D) present on segments 2, 4, 5, 7, 9, 11, 13 and 15 (all elytra missing).

Cirrigerous segments with distinct, cylindrical dorsal cirrophores ( Fig. 21C), inserted subdistally on notopodia; styles missing; dorsal tubercles present, forming cirriform branchial-like processes, small on segment 3, longest on segment 10 (as long as elytrophore of segment 9; Fig. 21D).

Ventral cirri smooth, tapering, present from segment 2 to last segment; inserted basally on neuropodia of segment 2, style long (longer than tip of neuroacicular lobe); in subsequent segments inserted medially on neuropodia ( Fig. 21C), style short (shorter than tip of neuroacicular lobe).

Parapodia subbiramous; notopodia shorter than neuropodia ( Fig. 21C). Notopodia arising from the dorsum, as two thickened ridges; notopodia subtriangular, tapering into long acicular lobe, tip of notoacicula not penetrating epidermis. Neuropodia large, rectangular to subtriangular, tapering into long acicular lobe, tip of neuroacicula not penetrating epidermis. Notochaetae few (six to 11 observed), short to long, slender, slightly curved, with developed spinous rows on convex side, with pointed tips ( Fig. 21E); notochaetae as stout as neurochaetae. Neurochaetae moderate in number (23– 30 observed), short to long, distally flattened to concave, serrated along both margins, with pointed tips ( Fig. 21F); lower group very short, leaf like ( Fig. 21G).

Nephridial papillae absent. Pygidium rounded, not enclosed by last segment; with dorsal anus ( Fig. 21A). Anal cirri lost, scars not seen.

Etymology: This species is dedicated to Dr Daniel Desbruyères (Laboratoire Environnement Profond, Ifremer, Brest, France) for his many contributions to the taxonomy and ecology of polychaetes mainly from extreme environments.

Remarks: This species shares many similarities with Yodanoe sp. 659-3 but the palps are shorter in Yodanoe desbruyeresi gen. nov., sp. nov. (reaching segment 5) than in Yodanoe sp. 659-3 (reaching segment 7). Moreover, the K2P distance between these species was high (24.0% for COI and 19.3% for 16S).

Genetic data: DNA sequencing for this species was successful for COI and 16S but not for 18S.

Distribution: Only one specimen was sampled at a single station within the Clarion-Clipperton Fracture Zone in Ifremer license area (type locality).